Thermal Stability and Kinetic Study on Thermal Degradation of Vitamin D_3 in Fortified Canola Oil

摘要

Nowadays, fortified vegetable oils with vitamin D-3 are widely available in different countries and are consumed daily. The reduction rate of added vitamin D-3 in fortified canola oil during heating process, the changes in oxidative status, and the thermal kinetic degradation of vitamin D-3 in the fortified oil were investigated. For this purpose, canola oil was fortified at two levels of vitamin D-3 with 5.625 mu g/mL (low concentration or LC) and 13.585 mu g/mL (a high concentration or HC). Samples were heated isothermally at 100, 150, and 180 degrees C for 30 min. The vitamin D-3 concentration was determined by the high-performance liquid chromatographic method. The retention of vitamin D-3 in samples treated at 100 degrees C for 30 min showed no significant reduction. Samples treated at 150 and 180 degrees C depending on the initial concentration showed the retention of 67.5% to 72.97% and 33.16% to 40.35% of vitamin D-3, respectively. An inverse relationship was found between the increment of lipid oxidation products (peroxide and anisidine values) and the retention of vitamin D-3. Kinetic parameters such as rate constant, activation energy, decimal reduction time, and quotient indicator were also calculated. An Arrhenius relationship was used for the assessment of temperature dependence of vitamin D-3 degradation. Activation energies for vitamin D-3 in LC and HC between 100 and 180 degrees C were found to be 44.01 and 38.77 kJ/mol, respectively. Practical Application The oil can be fortified with vitamin D-3 at low cost and offers a good bioavailability. A high-temperature cooking method may not be appropriate for the fortified products containing high lipid content.